In a nuclear reactor there are numerous pipes, pipe sockets and the like, in which cracks, especially in the vicinity of welds, may arise and where, during repair work, one end of the pipe may be released so as to form an open end for the fitting of a sealing sleeve. A plurality of various types of sealing sleeves are known--also such of memory metal (see, e.g., U.S. Pat. Nos. 4,773,680 and 4,149,911).
Characteristic of these sleeves is that they are not suited for sealing of pipe joints, for example control rod drive (CRD) stub tubes in a nuclear reactor, in which the pipes on either side of the joint are eccentrically arranged. Nor are they adapted to withstand the dimensional changes, caused by the temperature, which occur in a nuclear reactor in which the temperature varies from about +40.degree. C. to about +280.degree. C.